/Engine/Source/Runtime/Slate/Public/Widgets/Views/STreeView.h
Info needed by every visible item in the tree
struct FItemInfo
uint32:  1
bHasChildren
Does this tree item have children?
uint32:  1
bIsLastChild
Is this the last child of its parent? If so, it gets a special kind of wire/connector.
TBitArray
NeedsVerticalWire
Flags for whether we need a wire drawn for this level of the tree.
int32
ParentIndex
Indexinto the linearized tree of the parent for this item, if any, otherwise INDEX_NONE.